Wireless Communication Base Station Device, Wireless Communication Mobile Station Device, and Propagation Path Estimation Method

1. A user equipment (UE) apparatus comprising: a receiver configured to receive data and UE-specific reference signals, which are mapped to a plurality of resource blocks each formed of multiple subcarriers, the plurality of resource blocks being grouped into resource block group(s) and a resource block group being a unit in which a same precoder is applied; and an estimator configured to perform a downlink channel estimation based on the UE-specific reference signals, wherein the estimator applies a smoothing operation to a result of the downlink channel estimation over two or more resource block groups, if two or more precoders respectively applied in the two or more resource block groups are continuous in a frequency domain.

2. The UE apparatus according to claim 1 , wherein the estimator performs the downlink channel estimation based additionally on the number of resource blocks that constitute one resource block group.

3. The UE apparatus according to claim 2 , wherein the estimator estimates a precoder for each resource block group based on the UE-specific reference signals.

4. The UE apparatus according to claim 1 , wherein the precoder is a precoding matrix.

5. The UE apparatus according to claim 1 , wherein the same precoder is applied to the UE-specific reference signals mapped to the resource 1 blocks included in the resource block group.

6. A demodulation method comprising: receiving data and UE-specific reference signals, which are mapped to a plurality of resource blocks each formed of multiple subcarriers, the plurality of resource blocks being grouped into resource block group(s) and a resource block group being a unit in which a same precoder is applied; and performing a downlink channel estimation based on the UE-specific reference signals; and applying a smoothing operation to a result of the downlink channel estimation over two or more resource block groups, if two or more precoders respectively applied in the two or more resource block groups are continuous in a frequency domain.

7. The demodulation method according to claim 6 , further comprising: performing a downlink channel estimation based additionally on the number of resource blocks that constitute one resource block group.

8. The demodulation method according to claim 7 , further comprising estimating a precoder for each resource block group based on the UE-specific reference signals.

9. The demodulation method according to claim 6 , wherein the precoder is a precoding matrix.

10. The demodulation method according to claim 6 , wherein the same precoder is applied to the UE-specific reference signals mapped to the resource blocks included in the resource block group.